Non-ferrous metal ingots and billets are formed by a casting process, which utilizes a vertically oriented mold situated above a large casting pit beneath the floor level of the casting facility. The lower component of the vertical casting mold is a starting block mounted on starting block pedestals. When the casting process begins, the starting blocks are in their upward-most position and in the molds. As molten non-ferrous metal is poured into the mold and cooled, the starting block is slowly lowered at a pre-determined rate by a hydraulic cylinder or other device. As the starting block is lowered, solidified non-ferrous metal or aluminum emerges from the bottom of the mold and ingots or billets are formed.
While the invention applies to casting of non-ferrous metals, including aluminum, brass, lead, zinc, magnesium, copper etc., the examples given and preferred embodiment disclosed are for aluminum, and therefore the term aluminum will be used throughout for consistency even though the invention applies more generally to non-ferrous metals.
While there are numerous ways to achieve and configure a vertical casting arrangement, FIG. 1 illustrates one example. In FIG. 1, the vertical casting of aluminum generally occurs beneath the elevation level of the factory floor in a casting pit. Directly beneath the casting pit floor 1a is a caisson 3, in which the hydraulic cylinder barrel 2 for the hydraulic cylinder is placed.
As shown in FIG. 1, the components of the lower portion of a typical vertical aluminum casting apparatus, shown within a casting pit 1 and a caisson 3, are a hydraulic cylinder barrel 2, a ram 6, a mounting base housing 5, a platen 7 and a starting block base 8, all shown at elevations below the casting facility floor 4.
The mounting base housing 5 is mounted to the floor 1a of the casting pit 1, below which is the caisson 3. The caisson 3 is defined by its side walls 3b and its floor 3a.
A typical mold table assembly 10 is also shown in FIG. 1, which can be tilted as shown by hydraulic cylinder 11 pushing mold table tilt arm 10a such that it pivots about point 12 and thereby raises and rotates the main casting frame assembly, as shown in FIG. 1. There are also mold table carriages which allow the mold table assemblies to be moved to and from the casting position above the casting pit.
FIG. 1 further shows the platen 7 and starting block base 8 partially descended into the casting pit 1 with billet 13 being partially formed. Billet 13 is on starting block 14, which is mounted on pedestal 15. While the term starting block is used for item 14, it should be noted that the terms bottom block and starting head are also used in the industry to refer to item 14, bottom block typically used when an ingot is being cast and starting head when a billet is being cast.
While the starting block base 8 in FIG. 1 only shows one starting block 14 and pedestal 15, there are typically several of each mounted on each starting block base, which simultaneously cast billets or ingots as the starting block is lowered during the casting process.
When hydraulic fluid is introduced into the hydraulic cylinder at sufficient pressure, the ram 6, and consequently the starting block base 8, are raised to the desired elevation start level for the casting process, which is when the starting blocks are within the mold table assembly 10.
The lowering of the starting block base 8 is accomplished by metering the hydraulic fluid from the cylinder at a pre-determined rate, thereby lowering the ram 6 and consequently the starting blocks at a pre-determined and controlled rate. The mold is controllably cooled during the process to assist in the solidification of the emerging ingots or billets, typically using water cooling means.
The vertical semi-continuous casting process generally utilizes a mold table which contains and distributes cooling water to the individual molds. In an effort to maximize the number of billets which can be cast during any one lowering of the hydraulic cylinder, mold tables generally consist of a single or unitized spray box which delivers water to each mold from a common cavity.
There are numerous mold and pour technologies that fit into these mold tables. Some are generally referred to as "hot top" technology, while others are more conventional pour technologies that use floats and downspouts, both of which are known to those of ordinary skill in the art. The hot top technology generally includes a refractory system and molten metal trough system located on top of the mold table, whereas the conventional pour technology involves suspending the source of molten metal above the mold table and the utilization of down spouts or tubes and floats to maintain the level of molten metal in the molds while also providing molten metal to the molds.
These different casting technologies have different advantages and disadvantages and produce various billet qualities, but no one of which is required to practice this invention. Therefore any versatile or universal mold table system must be designed to support any of these different technologies and systems.
The metal distribution system is also an important part of the casting system. In the two technology examples given, the hot top distribution trough sits atop the mold table while the conventional pouring trough is suspended above the mold table to distribute the molten metal to the molds.
Mold tables come in all sizes and configurations because there are numerous and differently sized and configured casting pits over which mold table are placed. The needs and requirements for a mold table to fit a particular application therefore depends on numerous factors, some of which include the dimensions of the casting pit, the location(s) of the sources of water and the practices of the entity operating the pit.
The upper side of the typical mold table operatively connects to, or interacts with, the metal distribution system. The typical mold table also operatively connects to the molds which it houses. Precision in the location of the operative connections is therefore critical to proper interconnection of the mold table and to the resulting quality of the billets and ingots being cast.
It has been the longstanding practice to manufacture mold tables using a process which requires numerous different and discrete steps, i.e. the metal plate construction method. It has been long recognized that the metal plate construction method involves too many steps and requires too much time, money and labor. The metal plate construction method is a very time consuming and expensive process wherein the manufacturer starts with two metal plates which are the approximate dimensions of the desired mold table. Metallic tubes are interconnected to form a water frame, which is then placed between and attached to each of the two metal plates.
Once the two metal plates are attached to and around the water frame, the multi-step custom manufacturing process begins. The mold cavities and other requisite holes are drilled in each metal plate. Custom design work and engineering is generally necessary to obtain maximum mold density and sizing and substantial custom machining and fitting is required to construct the mold table. This general process is known by those of ordinary skill in the art.
The need for a simplified mold table system which minimizes the amount of custom design and engineering has been long recognized, but has not been adequately fulfilled by prior known machinery or methods. Fulfilling this need will result in substantial cost savings and reduced delivery time in the manufacture of mold tables.
In accomplishing these objectives through the use of a modular construction and frame system, this invention achieves the advantages of lower costs, lower manufacturing time, minimization of custom engineering and minimization of custom manufacture.
Aluminum and other non-ferrous metal manufacturers strive to obtain the highest mold density, i.e. to simultaneously cast the maximum number of billets for a given mold table size or pit. Maximizing mold density depends upon the size of the billets desired, the number of billets desired, the type of billet being cast, and different combinations thereof. Designing to maximize density for a given mold table application therefore generally involves substantial custom design work under the conventional metal plate construction method.
The way this invention uses pre-designed and standard components allows mold modules to be designed and optimized once for many of the design objectives, mold density being one example. The same module, once designed, can be used in many different applications without a need to redesign the primary elements. In accomplishing the objectives of simplifying and standardizing mold tables and their manufacture, this invention has the additional advantage of achieving maximum mold density for a given casting pit or mold table, while minimizing the custom engineering required by conventional systems.
It is also an objective of this invention to provide an improved water or coolant distribution system which effectively works in combination with the water passageway in the longitudinal and transverse headers and the modules. This invention accomplishes this objective by providing a water distribution system which includes a relatively easy operative connection between the coolant passageways in the longitudinal headers and an internal cavity within the mold modules.
The operative coolant connection between the coolant passageway in the longitudinal header and the internal cavity of the mold module is made during the process of attaching the modules to the longitudinal headers. Making the operative connection generally involves drilling a hole in the top of the longitudinal header to the coolant passageway and drilling a corresponding hole up through the lower surface of the overlap section of the mold module. The two corresponding holes are aligned and sealed during the attachment of the mold module to the longitudinal headers.
The water distribution system provided by this invention supplies water to the mold modules and to the molds without requiring as much plumbing and more complex and custom connections heretofore used in the industry. The modular system provided by this invention does not require that the metal plates first be attached to the frame and then manufactured sequentially as one unit. Instead, this invention allows the simultaneous manufacture, assembly and drilling of the longitudinal and transverse headers separate and apart from the manufacture of the mold modules. The mold modules can be manufactured by casting and then machining to specification. Once independently or simultaneously manufactured, the various components can then be assembled. The numerous advantages and consequent cost and time savings from this invention are therefore obvious and easily recognized by those of ordinary skill in the art.
The currently available mold tables include an oil plumbing system to provide oil to the molds for casting. Substantial custom design and custom manufacture of the plumbing is required to provide oil to the end of each of the rows of molds and then again to provide oil from the end of the row to each individual mold. Further, a substantial amount of plumbing and piping hardware is required to accomplish this. The custom design and manufacture currently practiced in the industry is much more time consuming, non-uniform and costly than it need be.
This invention accomplishes the objective of minimizing the amount of custom design and manufacture of the oil distribution system by providing an oil passageway through the extruded longitudinal headers. By placing an oil passageway in the longitudinal header, oil is supplied and provided along the entire length of the longitudinal headers, i.e. to the end of each row of mold modules. The oil passageway in the longitudinal header can be easily tapped into by partially drilling through the top of the longitudinal header to the passageway. A corresponding hole can also be drilled through the end of the mold module to form a passageway to the top of the mold module where the oil injector manifold can be located. An 0-ring can be placed between the mold module and the top of the longitudinal header to seal the interconnection.
The oil passageway along the length of the longitudinal header can be formed as part of the extrusion process if the longitudinal headers are extruded.
Once the oil passageway in the longitudinal headers are tapped into, standard plumbing can be utilized to provide the oil to each of the molds in the adjacent mold module(s). However, as distinguished from prior practices, plumbing is only required from the longitudinal headers to the mold and not all along the longitudinal headers, as previously required.
Providing the oil through a passageway in the longitudinal headers has the advantages of: reducing the custom design and manufacture of the plumbing that would otherwise be needed; reducing the time and hardware to manufacture and assemble a mold table; and simplifying the manufacture and assembly of the mold tables.
The gas distribution system in conventional mold tables has substantially the same problems that oil distribution systems have. This invention accomplishes the same objectives in substantially the same way with substantially the same advantages as for the oil distribution system by also supplying and providing gas through a passageway along the length of the longitudinal headers.
It should be noted that both the oil and the gas distribution systems are options.
There is also a need to screen larger particles from the coolant before the coolant is utilized by the mold. This screening has heretofore been accomplished by individual screens located at each mold, which requires unnecessary additional time to clean each of the several screens. This invention utilizes a centralized screen located in the coolant passageway in the longitudinal and/or transverse headers, which has the advantage of easier access and less maintenance time.
The forenamed recognized needs have not heretofore been sufficiently fulfilled by existing mold table systems.